The present invention relates to an aircraft, and more particularly an aircraft designed for horizontal as well as vehicle flight.
In broad classification, aircraft are designated as fixed wing aircrafts or rotary wing aircraft. A fixed wing aircraft encompasses the bulk of commercial and military aircraft. Rotary wing aircraft traditionally encompass various types of helicopters and other vehicles where the propulsion system is primarily oriented for vertical lift, rather than horizontal flight, as is the case for a fixed wing aircraft.
Various types of aircraft have been implemented or proposed wherein the propulsion system translates from a horizontal plane to a vertical plane, or where an engine thrust is vectored between a horizontal plane and a vertical plane.
The ability of an aircraft to operate both in a horizontal flight mode and in a vertical lift/loitering mode can be advantageous, particularly in a certain application. Horizontal flight mode typically allows for higher speeds and greater range. Vertical flight mode allows for takeoffs and landings in small areas. Vertical flight mode also allows for a more precise loitering which may be useful for civil and military applications, e.g. for traffic reporting, police crime scene investigation, and military surveillance systems.
The particular manner in which an aircraft translates from horizontal to vertical mode is significant, as complex systems may be more expensive and subject to greater operational failure.
In addition to translation of the propulsion system or thrust directions, other aircraft systems or payloads may also need to translate relative to the orientation of the propulsion system, or relative to the direction of flight.
For example, payloads may include guidance or surveillance systems which may be preferably forward looking doing horizontal flight, to facilitate navigation. However, when the aircraft is in a vertical/loitering flight mode it may be preferable to orient a surveillance system downwards, to continually view the area immediately below the aircraft. While mechanical scanning systems and electronic scanning systems, which operate to vary the boresight direction, are well known in the art, they commonly add expense, complexity, and weight to the payload. Such complexity and weight may be unacceptable, particularly where the aircraft is a small, unmanned aerial vehicle (UAV). Some UAVs weigh ten (10) pounds or less so the payloads must also be very light. In UAV implementations, use of a staring sensor, rather than a scanning sensor, may be preferable from a cost, weight, and complexity standpoint.
Accordingly, it is desirable to provide an aircraft that operates in both a horizontal flight mode and vertical flight mode, to provide a greater range and allow operation in small, and unimproved areas.
It is also preferable to provide an aircraft that includes a sensor or a surveillance payload which, in a horizontal flight mode is oriented in a horizontal plane, i.e. forward, but in a vertical flight mode, is oriented in a vertical plane, i.e. downward, without reorienting the sensor boresight angle relative to the fuselage.
It is further advantageous to implement these advantages in a UAV that is light weight, simple and relatively inexpensive.
These and other objects and advantages are implemented in the present invention, which is described below in relation accompanying drawings and claims.